====== Determination of the Absolute Configuration using - acetylated butyl glycosides ======

===== Introduction =====

see [[sop9|previous page]]

===== Procedure =====

  - Transfer sample (ca 0.2 mg, 1 µmol) to a 13 x 100 mm screw cap tube.
  - Hydrolyze in 0.5 mL 2M TFA at 120 °C for 30 min.
  - Evaporate the solution to dryness with a stream of compressed air, add 0.5 mL methanol and evaporate. Repeat once.
  - If the polysaccharide contains aminosugars, re-//N//-acetylate with 25 µL acetic anhydride for 4 h at room temperature. Evaporate with a stream of dry air.
  - Dissolve in 0.2 mL (+)-2-butanol. Add 15 µL acetyl chloride, bubble nitrogen through the solution for 30 sec., then seal the tube.
  - Butanolyze the sample for 8-16 h at 80 °C.
  - Evaporate the solution to dryness with a stream of air, add 0.5 mL methanol, then evaporate. Repeat once.
  - Acetylate with 0.2 mL acetic anhydride and 0.1 mL pyridine at 120 °C for 30 min.
  - Evaporate the solution and add 0.5 mL toluene and evaporate to dryness. Repeat once.
  - Partition between 0.5 mL H<sub>2</sub>O and 0.5 mL EtOAc. Transfer the upper (EtOAc) phase to a new tube. Repeat the extraction twice with 0.5 mL EtOAc. Concentrate the combined EtOAc phases to dryness, dissolve in 0.2 mL EtOAc, transfer to a new sample tube and concentrate to 25-50 µL.

===== References =====

  * G.J. Gerwig, J.P. Kamerling and J.F.G. Vliegenthart, //Carbohydr. Res.// **62** (1978) 349-357.
  * K. Leontein, B. Lindberg, J. Lönngren, //Carbohydr. Res.// **62** (1978) 359-362.
  * G.J. Gerwig, J.P. Kamerling and J.F.G. Vliegenthart, //Carbohydr. Res.// **77** (1979) 1-7 [[http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=519653| PubMed 519653]]